The New "Revolution" of Cell Therapy——Global R&D Overview of TCR-T Therapy

In recent years, tumor immunotherapy has become a hot spot in the field of anti-cancer.
In fact, tumor immunotherapy can be divided into two categories: one is to "tell" immune cells about the characteristics of the tumor, allowing them to locate and cause damage; the other One is to relieve the tumor's tolerance/shielding effect on immunity, allowing immune cells to re-recognize tumor cells and attack tumors (generally, tumor cells will cleverly disguise to escape immune surveillance)
.
In the first case, because the body’s own immune cells are used, it is currently mostly immune cell therapy; the latter is mainly to block the shielded immune signals, therefore, mostly small molecule drugs and antibody drugs, as we all know The PD-1/PD-L1 class
.
Of course, there are other categories that even work better in combination
.
The first case (immune cell therapy) has always been a research hotspot, including LAK, DC, CIK, DC-CIK, CAR-T, TCR-T, NK, CAR-NK, and tumor-infiltrating lymphocytes (TILs), etc.
etc.

_ But after more than a decade of research, the most effective and newest cell therapy approaches are CAR-T and TCR-T
.
At present, a number of clinical studies on TCR-T therapy are being carried out.
The existing results show that TCR-T has a good therapeutic effect, but there are also problems such as side effects that need to be solved urgently
.
In summary, this article will focus on the clinical research progress, current challenges and future development directions of TCR-T therapy
.
In 2002, Rosenberg's team first discovered that tumor infiltrating lymphocytes (TIL) isolated from melanoma can specifically kill tumor cells after in vitro expansion and infusion
.
However, in other tumors, TILs are often difficult to obtain and the expansion time in vitro is long.
After expansion, most of them are terminally differentiated T cells, and the sustained anti-tumor effect is weak.

.
In this context, people have explored whether the known antigen-specific TCR gene can be introduced into normal peripheral blood lymphocytes (PBL) for treatment, which is the origin of TCR-T cell therapy
.
An article published in Science by Rosenberg's group in 2006 showed that genetically modified TCR-T cells showed good application prospects in the treatment of melanoma - 2 of the 17 patients who participated in the trial showed Anti-tumor response, this study demonstrated for the first time the feasibility of genetically modifying TCR for tumor therapy
.
TCR-T technology has undergone four iterations in the development process: 01 The first generation of TCR-T is a subset of T cells that are specifically recognized by tumor antigens isolated from patient T cells, expanded in vitro and then reinfused for treatment
.
Due to the extremely small number of such T cell clones and large individual differences, it is difficult to industrialize
.
02 The second generation of TCR-T is to clone T cells specifically recognized by the above tumor antigens, obtain their TCR gene sequences, and then transduce them into peripheral T cells of patients.
This method makes it possible to industrialize TCR-T
.
03 The third-generation TCR-T optimizes the affinity of TCR to enable it to better recognize tumor antigens, and then transduce them to patient T cells to improve the overall drugability of TCR-T
.
04 The fourth-generation TCR-T is a highly specific cell therapy targeting tumor neoantigens (neoantigen), with greatly improved tumor response and safety
.
The full name of TCR-T is "T cell receptor engineered T cell therapy", which is also a new type of cellular immunotherapy
.
Mainly through gene editing technology, the T cell receptor (TCR) gene that can specifically recognize tumor antigens is introduced into the patient's own T cells to express exogenous TCR, which has the activity of specifically killing tumor cells.

.
T lymphocytes are known as the "warriors" in the human body.
They play an immune function in the human blood, lymph and surrounding tissues and organs, and can resist and eliminate tumor cells
.
However, in the process of tumor cell escape, T cells cannot recognize and kill tumor cells well
.
TCR (T cell receptor) is a specific receptor on the surface of T cells.
It binds to CD3 in a non-covalent bond to form a TCR-CD3 complex, which activates T cells by recognizing and binding antigens presented by MHC and promotes T cell division.
and differentiation
.
TCR-T therapy is a therapy in which a known antigen-specific TCR gene is introduced into normal peripheral blood lymphocytes
.
The introduction of new genes into ordinary T cells enables the engineered T cells to express TCRs that effectively recognize tumor cells, thereby guiding T cells to kill tumor cells
.
1 TCR-T and CAR-T therapy are the same (1).
One is that they both improve the ability of T cell receptors to recognize and attack specific cancer cell antigens by means of genetic modification, so they are collectively referred to as "T".
"T cell receptor redirection" technology; (2).
The second is that the treatment process is similar, in which the patient's own T lymphocytes are remodeled in vitro and then infused back into the patient
.
2 The difference between TCR-T and CAR-T therapy The difference between TCR-T and CAR-T therapy lies in the recognition mechanism of tumor cells
.
Although both are in vitro transformation of the patient's T cells and then infused back into the patient's body, CAT-T relies on an artificially designed single-chain antibody fragment (CAR), which can only recognize antigens on the surface of the tumor and pass intracellular Costimulatory molecules transmit signals that in turn activate T cells
.
While TCR-T is more similar to natural T cells in the human body, it mainly relies on affinity-optimized or pure natural TCR to recognize antigens presented by tumor MHC molecules, and transmit stimulatory signals to cells through the TCR-CD3 complex [3]
.
Therefore, TCR-T can not only recognize antigens on the tumor surface, but also recognize hundreds or thousands of antigens inside the tumor
.
It is this point that makes TCR-T more suitable for the treatment of solid tumors
.
In addition, the biggest challenge in the clinical application of CAR-T therapy is its toxic side effects, such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) [1]
.
The TCR of TCR-T is more natural and fully human, which fundamentally reduces the risk of cytotoxicity
.
1 Target/antigen screening Efficient TCR screening and development are common challenges in this field
.
Human tumor antigens are mainly divided into two categories: tumor-associated antigens (cancer-testis (CT) antigens, overexpressed antigens, differentiation antigens) and tumor-specific antigens (neoantigens, tumor virus antigens)
.
Although TCR-T can target all tumor antigens, the targets that have proved its safety and effectiveness are still limited.
Most of the targets in clinical trials of TCR-T are cancer-testis antigens and tumor virus antigens, of which the most NY-ESO, the number of development accounts for as high as 37%, latecomers should be vigilant not to push on this target
.
It is also difficult to screen TCRs with the best affinity threshold.
On the one hand, it is necessary to screen out those TCRs with high affinity for antigens to enhance the immune response, but it is also necessary to control their affinity.
The superphysiological TCR affinity will damage T cells, and the TCR Modification of the pHLA-binding properties can lead to unpredictable cross-reactivity against self-antigens, potentially leading to serious adverse events
.
The challenge of the latest generation of TCR-T technology for neoantigens is how to effectively identify such antigens
.
Kite Pharma uses HTS-IR technology and computational biology methods such as TraCeR and single-cell TCRseq at the cell population and single-cell levels to reconstruct TCR and identify immunogenic neoantigens; domestic pan-Bio and Kerui Biotechnology It uses flow sorting to sort T cells specific to tumor antigens of patients, and then uses single-cell technology to quickly obtain TCR genes that recognize such antigens, and then introduce them into peripheral T cells of patients for treatment
.
These explorations provide new tools for analyzing the diversity and dynamics of T cells, and more tools still need further development of bioinformatics technology
.
In addition, TCR must match the patient's human leukocyte antigen (HLA) alleles to recognize these pMHCs and kill cancer cells, so it is also very important to screen for appropriate HLA matching, which is why foreign TCR-T cannot One of the reasons for direct domestic application
.
2 Safety and quality control Toxic reactions and other adverse reactions caused by TCR-T off-target need to be verified by a complete quality verification system; uncertainty and safety caused by mismatches between exogenous TCR and endogenous TCR chains Risks should still be highly concerned, and various TCR restructuring strategies currently have their own advantages and disadvantages
.
Various schemes such as the design of TCR chain expression vector, the selection of elements, and the optimization of sequences can be used as important auxiliary means to improve the quality of receptor expression
.
3 Production system and cost TCR-T products are similar to CAR-T cell products in terms of production raw materials, production technology, process control, excipients, packaging containers, stability, etc.
Points to consider, such as the domestic "Guidelines for Research and Evaluation of Cell Therapy Products (Trial)", "Key Points to Consider for the Application of Clinical Trial Pharmacy Research and Application Materials for Cell Therapy Products" and foreign guidelines such as the US FDA and EU EMA related to advanced therapy
.
The production cost of TCR-T accounts for nearly 80% of the total cost of TCR-T.
How to reduce production costs and increase production capacity is critical to improving the availability of products for use in patients
.
In the field of cell therapy, product pricing has always been a topic of concern and discussion
.
Kymriah is priced at $475,000/course, and Yescarta is priced at $373,000/course.
The high price seems to have been seen as a label for cell therapy
.
Cost is indeed a problem, but with the expansion of the market scale and the improvement in all aspects of R&D and processes, cost reduction is an inevitable trend, which is the direction that the entire industry is working towards
.
4 Overcome immune escape Tumor immune escape refers to the phenomenon that tumor cells can survive and proliferate in the body by evading the recognition and attack of the body's immune system through various mechanisms
.
Solid tumors themselves are characterized by a complex immunosuppressive microenvironment and inherent heterogeneity, and current TCR-T induction of durable responses remains challenging
.
Refer to CAR-T solutions: First, by modifying T cells to release cytokines to counteract the immunosuppressive factors in the tumor microenvironment; Second, with the tumor microenvironment (TME, there are many cells in the tumor microenvironment, including tumor cells , fibroblasts, immune cells, various signaling molecules and extracellular matrix, etc.
The tumor microenvironment significantly affects the diagnosis, survival outcome and clinical treatment sensitivity of tumors, and the microenvironments of different tumor tissues have their own characteristics) inhibitors Combined use
.
On January 25, 2022, Kimmtrak (tebentafusp-tebn), an immunotherapy developed by Immunocore, was recently approved by the US FDA
.
For adult patients with HLA-A*02:01-positive unresectable or metastatic uveal melanoma (mUM)
.
The approval of Kimmtrak has achieved multiple "firsts" and has become a major breakthrough with milestones: the first FDA-approved TCR-T therapy; the first FDA-approved bispecific T for solid tumors Cell Engager; the first and currently only FDA-approved therapy for unresectable or metastatic uveal melanoma
.
1 International progress The global TCR-T therapy mainly targets the solid tumor market and has become a research hotspot internationally
.
According to incomplete statistics, one product, Kimmtrak, has been marketed at home and abroad, and 53 drugs are in the clinical stage or above, most of which are in the I/II stage and the early preclinical stage.
The indications include metastatic non-small cell lung cancer, hepatocyte cancer, multiple myeloma, soft tissue sarcoma, head and neck cancer, melanoma, liposarcoma, cervical cancer,
etc.
1.
Adaptimmune Adaptimmune was established in 2008 and listed on Nasdaq in May 2015, with a market value of US$555 million as of July 30, 2021
.
The company's unique SPEAR (Specific Peptide Enhanced Affinity Receptor) T cell platform enables T cells to target and destroy a variety of malignant tumor cells, including solid tumors, through the transformation of T cells
.
The company's first product, NY-ESO, has been transferred to GSK, and GSK has the exclusive right to develop and promote it worldwide
.
At present, the company's product MAGE-A4 is in clinical phase II, and AFP is in clinical phase
I.
2.
Adaptive Adaptive Biotechnologies, founded in 2009 under the original name Adaptive TCR Corporation, is a company that transforms the diagnosis and treatment of disease by harnessing the inherent biology of the adaptive immune system
.
In January 2019, Adaptive reached a cooperation with Genentech, a subsidiary of Roche
.
Adaptive will use its investigational TCR discovery platform to screen for the best TCRs in patients, Genentech will design and manufacture TCR-T drugs based on the biological information provided by Adaptive, Adaptive Biotechnologies has become a star company in the TCR-T field
.
Its TruTCR screening platform enables the identification and characterization of TCRs that efficiently bind target antigens through immunosequencing and other techniques
.
3.
MediGene Founded in 1994, Medigene is a biotechnology company headquartered in Munich, Germany, dedicated to the development of TCR-T and DC vaccines
.
4.
TCR2 TCR2 Therapeutics was established in 2015, and completed a $44.
5 million Series A financing in October of that year, and went public on Nasdaq in February 2019
.
The company lives up to its name with a focus on developing TCR therapies
.
TCR2 has a unique technical advantage, that is, the TRuCTM platform, which has the advantage of including the complete TCR complex itself without HLA matching
.
By directly linking tumor antigen binders such as scFV, sdAb, and Fab to the TCR complex, the new structure can recognize antigens highly expressed on the surface of tumor cells without the need for HLA, and utilize the complete TCR mechanism to activate T cells function
.
Currently, the company has a TCR-T product in Phase I clinical trials
.
5.
RootPath RootPath is a preclinical stage biotechnology company that utilizes world-leading ultra-high-throughput DNA fragment assembly and gene synthesis technologies to pioneer the development of a synthetic immunology platform that enables individualized, polyclonal, tumor response Sexual TCR-T therapy becomes possible
.
RootPath's technology can solve three problems at the same time: 1) Use multiple TCRs to avoid escape; 2) Use autologous TCRs to ensure safety; 3) Use peripheral blood T cells as carriers to ensure the function of T cells
.
RootPath's current focus is on moderately immunogenic solid tumors, including colorectal cancer, non-small cell lung cancer, head and neck cancer, and gastric cancer
.
2 Domestic progress The number of domestic TCR-T clinical applications ranks second in the world, and domestic TCR-T companies include Xiangxue Precision, Tiankeya, Kerui Bio, Utijisheng, Shenzhen Innoimmune, Guangzhou Laien Biomedicine, Beijing Kerui Bio, of which Xiangxue Life's new high-affinity TCR-T drug TAEST16001 has obtained the first TCR-T clinical trial license in China
.
1.
Xiangxue Precision Xiangxue Precision Medical Technology Co.
, Ltd.
(XLifeSc) was established in 2015.
It is a pharmaceutical company with international leading-edge biotechnology based on cellular immunotherapy
.
XLifeSc is mainly committed to the research and development of a new method for tumor-specific T cell adoptive immunotherapy (TCR-T immunotherapy technology) with China's independent intellectual property rights.
This technology is innovative, unique and efficient, reaching the international advanced level.

.
XLifeSc has established a full-coverage R&D platform from TCR-T product R&D, preparation, quality control, product industrialization to clinical transformation, and has a product pipeline covering most genotypes of the population
.
At present, XLifeSc has successfully developed autologous T cell therapy (TAEST) transduced by antigen-specific high-affinity T cell receptors.
A TCR-T cell drug that has entered a registration-based clinical trial
.
2.
Tiankeya Tiankeya focuses on the R&D and industrialization of tumor immune cell therapy.
Its TCR/CAR-T development platform, virus and cell transformation and production technology platform are in an international leading position
.
The company has three platforms: 1) The TRUST platform uses tools including single-cell sequencing and transcriptome data analysis to simultaneously analyze the transcriptional level and functional role of TCR to reduce the false positive rate.
At present, the company uses the TRUST platform to screen out more than 20 new Target TCR; 2) CHECK-T technology platform, using virus to transform T cells
.
Two sequences are loaded into the virus to express TCR and components that fight against the tumor microenvironment and reduce immunosuppression, respectively, and then transfect T cells to make TCR-T products; 3) TURBO-T responds to the problem of tumor heterogeneity.
-In the development of T products, tumor microenvironment repair factors are loaded to stimulate in vivo immunity to fight tumor heterogeneity
.
The first batch of the company's pipelines entering clinical trials targets tumors caused by viral infections, such as EBV and HPV, and is currently in the IIT stage
.
3.
Kerui Bio was co-founded by a number of Peking University alumni and returnees from overseas studies.
It is committed to the research and development of anti-tumor immunotherapy technology, the development and service of gene editing products, and the exploration of gene therapy for genetic diseases
.
The existing TCR optimization needs to go through complex and tedious in vitro mutation library establishment, phage display and affinity optimization, etc.
, and cannot obtain the optimal therapeutic TCR
.
In response to these bottlenecks, Kerui Bio has developed the TCR affinity optimization technology SMART-TCR, which simplifies and improves the existing TCR scheme
.
The SMART-TCR system is also divided into three modules: 1) Preparation of a diversity library of TCRs; 2) Obtaining high-affinity TCRs through positive selection; 3) Excluding non-specific TCRs through negative selection
.
The SMART-TCR system has two typical characteristics: 1) The efficiency of the entire system is very high.
It is a closed-loop system that operates in a closed loop.
It can continuously perform multiple rounds of affinity evolution to gradually increase the affinity.
When the entire system is running, it needs to be less manpower
.
2) The company has integrated the module of non-specific exclusion in the system, which makes the TCR output from the system improve the affinity without non-specific reaction to human normal antigens.

.
The company will start patient recruitment for "advanced cervical cancer TCR-T cell products" in the second half of 2021, initiate IIT preparation for colorectal cancer/pancreatic cancer, and have MAGE, AFP and bispecific TCR protein drugs with multiple targets Product is under research
.
4.
Eutejisheng Eutejisheng's strategy is based on the cell engineering technology platform, transforming T cells themselves, and at the same time reversing the tumor microenvironment to make TCR-T or CAR-T play a better role, avoiding immune escape problem
.
The company's core technology, LACO-stim, aims to enhance T cell function by reversing the tumor microenvironment, such as converting the signal of the PD-L1/PD-1 inhibitory immune microenvironment into a "second signal" for T cells, The inhibitory effect of the microenvironment on T cells also makes T cells have stronger killing ability and longer persistence
.
The products developed by Eutegene have selected four relatively safe targets: CD19, NY-ESO-1, Mesothelin, and HER2.
The indications cover hematological tumors and solid tumors.
The products are all in the preclinical drug discovery stage
.
Immunocore and Adaptimmune have grown from cutting-edge to leaders, and domestic and foreign pharmaceutical giants Novartis, Hengrui, and Fosun have also quietly deployed.
The effect of TCR-T on solid tumors is worth looking forward to.
Although there are still shortcomings, with the innovation of technology And accumulation, let us see that mankind is getting closer and closer to the day of conquering cancer
.
*Declaration: Due to the limited level of the author, if there are any deficiencies in the content and statistics, please add and correct
.
References: 1.
https:// https:// 3.
https:// mp.
weixin.
qq.
com/cgi-bin/home?t=home/index&token=1978502775&lang=zh_CN4.
https:// 6.
https://ir.
immunocore.
com/static-files/71d9be4d- bf60-4148-84ba-9e7560962ce4 7.
Toubao "Research Progress and Application Prospects of TCR-T Therapy in China in 2021" 8.
Shenghui: Regresses solid tumors, the disease control rate is 100%, this company combines CAR and TCR What is the difference? 9.
Official website of each company